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A231643
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a(n) = 5*2^n + 5.
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4
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10, 15, 25, 45, 85, 165, 325, 645, 1285, 2565, 5125, 10245, 20485, 40965, 81925, 163845, 327685, 655365, 1310725, 2621445, 5242885, 10485765, 20971525, 41943045, 83886085, 167772165, 335544325, 671088645, 1342177285, 2684354565, 5368709125, 10737418245
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OFFSET
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0,1
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COMMENTS
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For n > 2, decimals given by base 2 pattern: 101...zeros...101.
The ratio between a(n) and a(n+1) tends to 1/2.
Sum(1/a(i), i=0..infinity) = ( psi_2^(0)( 1 - i*Pi/log(2) ) + i*Pi ) / log(32) = 0.252899956069688841838263949451..., where psi_q^(m)(.) is the m-th derivative of the q-digamma function. [Bruno Berselli, Nov 15 2013]
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LINKS
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FORMULA
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a(n) = 3*a(n-1)-2*a(n-2) for n>1, a(0)=10, a(1)=15. - Philippe Deléham, Nov 15 2013
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MATHEMATICA
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Table[5*2^n + 5, {n, 0, 50}] (* T. D. Noe, Nov 15 2013 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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